Amount of substance (AS)

The Ideal Gas Equation

Formula is pV = nRT

• p is pressure in Pa (Pascals)
• V is volume in m³ (metres-cubed)
• n is moles (no units)
• R is the gas constant which is 8.31JK^-1 mol^-1 (Note: You do not need to remember this as it will be give to you in the exam)
• T is temperature in K (Kelvin)

How to work out

• 1 atm is 100,000 Pa or 101,000 Pa
• 100 kPa is 100,000 Pa

• From degrees Celsius°C to K add+273 to the value
• m³ to dm³ multiply by 1,000
• m³ to cm³ multiply by 1,000,000
• Standard conditions is 100,000 Pa and 298K